1. Field of the Invention
The present invention generally relates to devices having a resin package such as semiconductor devices, and more particularly to a resin-sealed semiconductor device of a leadless surface mounting type directed to high-density mounting. Further, the present invention is concerned with a method of producing such a semiconductor device.
Recently, down-sizing of electronic devices has required a decrease in the pitch of leads extending from a resin-sealed type package.
Hence, it is desired that there are provided a new structure of the resin-sealed type package making it possible to further decrease the lead pitch and a method of producing such a structure.
2. Description of the Related Art
FIGS. 1A, 1B and 1C are diagrams of a semiconductor device having a conventional resin-sealed package. The device includes a resin 1, a chip 2, outer leads 3, bonding wires 4 made of an alloy of gold and aluminum (Au-Al), and a die pad 5.
The package shown in FIGS. 1A, 1B and 1C is called an SSOP (Shrink Small Outline Package). The outer leads 3 are bent in a gull-wing shape, and are mounted on a circuit board.
FIG. 2 is a cross-sectional view of a semiconductor device of another type. The device shown in FIG. 2 includes solder balls 6 and a mount base 7 on which the chip 2 sealed by the resin 1 and solder balls 6 are provided. The package shown in FIG. 2 is called a BGA (Ball Grid Array) type, and the solder balls 6 serve as terminals provided on the mount base 7.
The SSOP type package shown in FIGS. 1A, 1B and 1C has a disadvantage in which a large area 9 is needed to arrange inner leads 8 integrally formed with the outer leads 3, and a large area is needed to arrange the outer leads 3. Hence, the SSOP type package needs a large mounting area.
The BGA type package shown in FIG. 2 is expensive because it needs the mount base 7.
It is an object of the present invention to provide a semiconductor device and its fabrication method and to provide a lead frame and its fabrication method in which semiconductor devices can be fabricated and tested efficiently.
The above object of the present invention is achieved by a semiconductor device comprising: a semiconductor element; a resin package sealing the semiconductor element; resin projections protruding downward from a mounting surface of the resin package; metallic film portions provided to the resin projections; and connecting members electrically connecting the semiconductor elements to the metallic film parts, outer circumference surfaces of the resin package being upright surfaces defined by cutting.
The above object of the present invention is also achieved by a lead frame used for fabricating a semiconductor device including: a semiconductor element; a resin package sealing the semiconductor element; resin projections protruding downward from a mounting surface of the resin package; metallic film portions provided to the resin projections; and connecting members electrically connecting the semiconductor elements to the metallic film parts, wherein outer circumference surfaces of the resin package are upright surfaces defined by cutting, the lead frame comprising: a base member; recess portions formed in the base member and located in positions corresponding to the resin projections; and a metallic film provided in the recess portions, the metallic film parts being formed from the metallic film.
The above object of the present invention is also achieved by a method for producing a lead frame used to fabricate a semiconductor device, the method comprising the steps of: (a) providing etching resist layers on opposing surfaces of a base member of the lead frame; (b) removing portions corresponding to recess forming portions from one of the etching resist layers; (c) forming recess portions in the base member so as to correspond to the recess forming portions; (d) forming a metallic film in the recess portions; and (e) removing the etching resist layers.
The above object of the present invention is also achieved by a method for producing a lead frame used to fabricate a semiconductor device, the method comprising the steps of: (a) providing etching resist layers on opposing surfaces of a base member of the lead frame; (b) removing portions corresponding to recess forming portions from one of the etching resist layers; (c) forming recess portions in the base member so as to correspond to the recess forming portions; (d) removing the etching resist layers; (e) providing plating resist layers on the opposing surfaces of the base member; (f) removing portions of one of the plating resist layers corresponding to the recess forming positions; (g) forming a metallic film in the recess portions in the base member by plating; and (h) removing the plating resist layers.
The above object of the present invention is also achieved by a method for fabricating semiconductor devices comprising the steps of: (a) mounting semiconductor elements on a lead frame including a base member, recess portions formed in the base member and located in positions corresponding to the resin projections, and a metallic film provided in the recess portions so that metallic film parts are formed in the recess portions; (b) electrically connecting the semiconductor element to the metallic film parts; (c) sealing the semiconductor elements on the lead frame by resin as a whole so that the semiconductor elements are sealed by a resin sealing body; (d) separating the semiconductor elements together with the metallic film parts from the lead frame; and (e) dividing the resin sealing body into respective resin packages.
The above object of the present invention is also achieved by a semiconductor device comprising: a plurality of elements including a semiconductor chip and/or an electronic element; a resin package sealing the plurality of elements; resin projections protruding from a mounting surface of the resin package downward; metallic film parts provided to the resin projections; and connecting members electrically connecting the elements to the metallic film parts, outer circumference surfaces of the resin package being upright surfaces defined by cutting.